Wiring prognostics system for vehicles

ABSTRACT

A system for a vehicle includes a battery of the vehicle, a plurality of switches connected to the battery, and a plurality of subsystems of the vehicle connected to the battery via the switches and wires. The system includes a controller configured to control the switches and the subsystems, and to identify a variation in a rate of change of current characteristic in frequency domain for a current loop including one of the switches, one of the subsystems, and a plurality of the wires. The controller is configured to determine integrity of the plurality of the wires and connections of the wires in the current loop based on the variation in the rate of change of current characteristic for the current loop.

INTRODUCTION

The information provided in this section is for the purpose of generallypresenting the context of the disclosure. Work of the presently namedinventors, to the extent it is described in this section, as well asaspects of the description that may not otherwise qualify as prior artat the time of filing, are neither expressly nor impliedly admitted asprior art against the present disclosure.

The present disclosure relates to a wiring prognostics system forvehicles.

A vehicle comprises many subsystems that include sensors and actuatorsthat are operated by one or more batteries in the vehicle. Examples ofthe subsystems include a braking subsystem, a steering subsystem, anavigation subsystem, a communication subsystem, an infotainmentsubsystem, a safety subsystem, an autonomous subsystem, and so on. Thesubsystems are connected to and communicate via a Controller AreaNetwork (CAN) bus in the vehicle.

The subsystems include components connected by wires (e.g., cables,wiring harnesses, etc.) and connectors. The wires and connectors candegrade over time due to various factors such as environmental andoperating temperatures, vibration, and so on. As a result, the wires andconnectors can develop problems including loose connections, openconnections, short circuits, corroded contacts, and so on. Theseproblems can cause inconveniences (e.g., the vehicle may fail to start)or jeopardize safety of occupants of the vehicle (e.g., a safety featuremay fail to operate).

SUMMARY

A system for a vehicle comprises a battery of the vehicle, a pluralityof switches connected to the battery, and a plurality of subsystems ofthe vehicle connected to the battery via the switches and wires. Thesystem comprises a controller configured to control the switches and thesubsystems, and to identify a variation in a rate of change of currentcharacteristic in frequency domain for a current loop including one ofthe switches, one of the subsystems, and a plurality of the wires. Thecontroller is configured to determine integrity of the plurality of thewires and connections of the wires in the current loop based on thevariation in the rate of change of current characteristic for thecurrent loop.

In another feature, the controller generates an indication regarding theintegrity of the plurality of the wires and connections of the wires inthe current loop in response to the integrity being less than or equalto a first threshold.

In another feature, the controller generates an indication regarding theintegrity of the plurality of the wires and connections of the wires inthe current loop in response to the integrity being less than or equalto a first threshold, and disconnects the one of the subsystems from thecurrent loop by controlling the one of the switches in response to theintegrity being less than or equal to a second threshold that is greaterthan the first threshold.

In another feature, the controller characterizes operation of the one ofthe subsystems based on the variation in the rate of change of currentcharacteristic for the current loop and determines based on thecharacterization whether to disconnect the one of the subsystems fromthe current loop by controlling the one of the switches.

In another feature, the controller characterizes operation of the one ofthe subsystems based on the variation in the rate of change of currentcharacteristic for the current loop, and based on the characterizationcontrols the one of the switches to disconnect the one of the subsystemsfrom the current loop and subsequently reconnect the one of thesubsystems to the current loop.

In another feature, the controller characterizes the operation of theone of the subsystems and disconnects the one of the subsystems based onthe characterization when the vehicle is turned off.

In another feature, based on the variation in the rate of change ofcurrent characteristic for the current loop, the controller disconnectsthe one of the subsystems from the current loop and activates a backupsubsystem powered by the battery.

In another feature, based on the variation in the rate of change ofcurrent characteristic for the current loop, the controller disconnectsthe one of the subsystems from the current loop and activates a backupsubsystem powered by a different battery.

In another feature, the controller determines the integrity of theplurality of the wires and connections of the wires additionally basedon one or more of a voltage measurement and a temperature measurement inthe current loop.

In another feature, the controller is configured to generate and store aset of histograms of rate of change of current characteristics measuredat different operating temperatures for the plurality of subsystems,generate a histogram of the rate of change of current characteristic atan operating temperature for the one of the subsystems, compare thehistogram to one of the histograms corresponding to the operatingtemperature, determine a difference between the histogram and the one ofthe histograms, determine the integrity of the plurality of the wiresand connections of the wires in the current loop based on thedifference, and generate an indication regarding the integrity of theplurality of the wires and connections of the wires in the current loopin response to the difference being greater than or equal to apredetermined threshold.

In still other features, a method comprises connecting a battery to aplurality of subsystems of a vehicle via a plurality of switches andwires, controlling the switches and the subsystems, and identifying avariation in a rate of change of current characteristic in frequencydomain for a current loop including one of the switches, one of thesubsystems, and a plurality of the wires. The method comprisesdetermining an integrity of the plurality of the wires and connectionsof the wires in the current loop based on the variation in the rate ofchange of current characteristic for the current loop.

In another feature, the method further comprises detecting at least oneof a defective wire and a defective connection of one of the wires inthe current loop.

In another feature, the method further comprises generating anindication regarding the integrity of the plurality of the wires andconnections of the wires in the current loop in response to theintegrity being less than or equal to a first threshold, anddisconnecting the one of the subsystems from the current loop bycontrolling the one of the switches in response to the integrity beingless than or equal to a second threshold that is greater than the firstthreshold.

In another feature, the method further comprises characterizingoperation of the one of the subsystems based on the variation in therate of change of current characteristic for the current loop, anddetermining based on the characterization whether to disconnect the oneof the subsystems from the current loop by controlling the one of theswitches.

In another feature, the method further comprises characterizingoperation of the one of the subsystems based on the variation in therate of change of current characteristic for the current loop, and basedon the characterization, controlling the one of the switches todisconnect the one of the subsystems from the current loop andsubsequently reconnect the one of the subsystems to the current loop.

In another feature, the method further comprises characterizing theoperation of the one of the subsystems when the vehicle is turned off,and disconnecting the one of the subsystems based on thecharacterization when the vehicle is turned off.

In another feature, the method further comprises based on the variationin the rate of change of current characteristic for the current loop,disconnecting the one of the subsystems from the current loop andactivating a backup subsystem powered by the battery.

In another feature, the method further comprises based on the variationin the rate of change of current characteristic for the current loop,disconnecting the one of the subsystems from the current loop andactivating a backup subsystem powered by a different battery.

In another feature, the method further comprises determining theintegrity of the plurality of the wires and connections of the wiresadditionally based on one or more of a voltage measurement and atemperature measurement in the current loop.

In another feature, the method further comprises generating and storinga set of histograms of rate of change of current characteristicsmeasured at different operating temperatures for the plurality ofsubsystems, generating a histogram of the rate of change of currentcharacteristic at an operating temperature for the one of thesubsystems, comparing the histogram to one of the histogramscorresponding to the operating temperature, determining a differencebetween the histogram and the one of the histograms, determining theintegrity of the plurality of the wires and connections of the wires inthe current loop based on the difference, and generating an indicationregarding the integrity of the plurality of the wires and connections ofthe wires in the current loop in response to the difference beinggreater than or equal to a predetermined threshold.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description, the claims and the drawings. Thedetailed description and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 shows an example of a wiring prognostics system for a vehicleaccording to the present disclosure;

FIG. 2 shows an example of the wiring prognostics system for a vehicleincluding redundant subsystems and a single battery;

FIG. 3 shows an example of the wiring prognostics system for a vehicleincluding redundant subsystems and a redundant battery;

FIG. 4 shows a portion of the wiring prognostics system includingtemperature, current, and voltage sensors;

FIG. 5 shows an example of a current loop including wires and connectorsdiagnosed by the wiring prognostics system;

FIG. 6 shows a graph of rate of change of current (di/dt) data versustime;

FIG. 7 shows a graph of rate of change of current (di/dt) data versusfrequency;

FIG. 8 shows a flowchart of a method performed by the wiring prognosticssystem to identify and isolate a current loop that drains the battery ofthe vehicle;

FIG. 9 shows a flowchart of a method performed by the wiring prognosticssystem to identify and isolate a misbehaving subsystem (e.g., notresponding, having communication issues, etc.) in the vehicle;

FIG. 10 shows a flowchart of a method performed by the wiringprognostics system for identifying and isolating a misbehaving safetysubsystem of the vehicle and switching to a backup safety subsystem inthe vehicle;

FIG. 11 shows a flowchart of a method for calibrating the wiringprognostics system;

FIG. 12 shows a flowchart of a method for empirically determining athreshold used by the wiring prognostics system;

FIG. 13 shows a flowchart of a first method performed by the wiringprognostics system to handle a failure of a wire and/or a connection ina current loop including a subsystem controlling a safety feature of thevehicle;

FIG. 14 shows a flowchart of a second method performed by the wiringprognostics system to handle a failure of a wire and/or a connection ina current loop including a subsystem controlling a safety feature of thevehicle;

FIG. 15 shows a flowchart of a method performed by the wiringprognostics system to detect and disable a current loop that is drainingthe battery of the vehicle when the vehicle is turned off;

FIG. 16 shows a flowchart of a method performed by the wiringprognostics system to detect and isolate a misbehaving subsystem in avehicle while the vehicle is turned off;

FIG. 17 shows a flowchart of a method performed by the wiringprognostics system to verify integrity of wiring and connections in avehicle before shipping the vehicle from the factory; and

FIG. 18 shows a flowchart of a method performed by the wiringprognostics system to verify integrity of wiring and connections in avehicle after servicing the vehicle at a service center before returningthe vehicle to the customer.

In the drawings, reference numbers may be reused to identify similarand/or identical elements.

DETAILED DESCRIPTION

Diagnostic methods such as time domain reflectometry (TDR) are typicallyused to diagnose wiring and connection problems in vehicles. However,these methods require additional hardware (e.g., diagnostic equipmentsuch as a cable tester and associated wiring), which introducesadditional failure points and yet cannot proactively perform prognosticsby detecting degrading performance of the wiring and connections beforea fault occurs. Moreover, measurements made using these methods aresusceptible to electrical noise.

Some subsystems (e.g., subsystems controlling safety features) in thevehicle may be provided with redundancy capabilities (e.g., a backupsubsystem, a redundant battery, etc.). However, providing redundancycapabilities increases cost. Further, although a backup subsystem for aprimary subsystem is provided for redundancy, presently there is no wayto automatically switch operation to the backup subsystem by proactivelydetecting a problem with the primary subsystem before the primarysubsystem fails. Such proactive problem detection and subsequentautomatic switching to backup (i.e., redundant) subsystems can be usefulin autonomous vehicles.

In addition, presently there is no way to provide a hardware reset(i.e., disconnecting and reconnecting power) to a subsystem in thevehicle if the subsystem is misbehaving (e.g., draining battery, notresponding, having communication issues, etc.). Presently there is alsono way to detect a subsystem that is draining battery while the vehicleis turned off and to disconnect the subsystem while the vehicle isturned off. Furthermore, presently there is no way to verify integrityof the wiring and the connections in a vehicle before shipping thevehicle from the factory or before returning the vehicle to the customerafter the vehicle is serviced at a service center.

The present disclosure provides a prognostics system that provides allof the above capabilities. The prognostics system characterizesimpedances of the wiring and the connections used in various subsystemsin the vehicle without using any additional equipment. The prognosticssystem detects degrading performance of the wiring and the connectionsbefore a fault occurs. The impedance characterization is carried out byanalysing rate of change of current (di/dt) data from various nodes(i.e., connection points) in the wiring in frequency domain. Unlike theconventional resistance measurements performed by measuring voltage andcurrent in time domain that are susceptible to noise, the analysis ofthe di/dt data in the frequency domain is largely unaffected by thenoise due to noise filtering built into the analysis process in thefrequency domain. Further, by increasing sampling frequency, theanalysis of the di/dt data in the frequency domain can be used to detectwiring abnormalities at a higher resolution than when the data isanalyzed in time domain. The ability to proactively identifyabnormalities reduces the need to provide redundancies for many systemsin the vehicles, which saves cost.

Additionally, instead of using conventional wire fuses, the prognosticssystem uses active switches (e.g., FET's) that can not only operate asfuses but can also be individually controlled to perform some of theoperations that are presently not possible (e.g., isolating amisbehaving subsystem, automatically switching operation to a backupsubsystem, providing hardware resets to subsystems, disconnecting asubsystem while the vehicle is turned off, etc.). The present disclosureis not limited to active switches. Instead, relays could be used.Further, the prognostics system can also work with fuses except that nomitigating or corrective actions can be performed. Further, theprognostics system can be used in the factory to verify the wiring andthe connections of the subsystems in vehicles before shipping thevehicles. The prognostics system can also be used at service centers toverify the wiring and the connections after servicing vehicles beforereturning the vehicles to customers. These and other features of theprognostics system are described below in detail.

Specifically, presently, vehicles have a limited capability toself-diagnose compromised power delivery systems resulting fromimproperly torqued connections, loose and/or corroded connections, anddamaged wires prior to permanent failure. Providing the ability toidentify degraded performance of the wires and the connections and tonotify customers prior to failure can improve safety and customersatisfaction. The prognostics system of the present disclosure canproactively detect these problems. The prognostics system provides anability to characterize and measure changes in impedance of the powerdelivery systems using frequency domain analysis of di/dt data collectedfrom the power delivery systems.

Many diagnostic systems may not detect problems associated with wiringand the connections in vehicles. The prognostics system of the presentdisclosure solves the following problems associated with thesediagnostics systems: inability to detect wiring and connectionperformance degradation, requirement for more than one battery in activesafety systems, limited safety performance in autonomous systems, andinability to force load shedding and isolation of subsystems duringfailure modes to prioritize safety.

The prognostics system of the present disclosure detects wiringconnection degradation in vehicles for wiring prognostics withoutrequiring additional external test equipment. The prognostics system canmonitor and set wiring fault detection thresholds using empiricaltesting and calibrations performed based on the empirical testing. Theprognostics system provides a built-in self-test of wiring systems thatcan be used in the factory before shipping vehicles and at servicefacilities before returning vehicles to customers after service. Theprognostics system allows use of a single battery system for activesafety feature support and provides enhanced system reliability.

More specifically, the prognostics system identifies changes in di/dtcharacteristics of a subsystem in frequency domain to characterizechanges in behavior of the subsystem and to analyze changes in impedanceover a current loop comprising the subsystem and associated wiring andconnections. The prognostics system identifies performance degradationin the wiring and the connections based on the changes in impedance. Theprognostics system sets wiring diagnostic threshold levels based on thedi/dt analysis performed in the frequency domain since a discernablechange cannot be identified over the noise floor when voltage, current,or power are analyzed in the time domain. In the frequency domain, thedi/dt rates decrease as connections become loose or otherwise degrade(e.g., due to corrosion, vibration, etc.), which allows the prognosticssystem to detect minute problems such as when a nut is loose by aslittle as a quarter turn, for example. The detection resolution can beincreased even further (e.g., to an eighth of a turn and so on) byincreasing the sampling frequency.

The prognostics system provides compensation for wiring diagnostics overvehicle operating conditions. The prognostics system identifies changesin wiring and connection integrity more easily than alternative methodsand with less sensitivity to noise associated with analog measurements.The prognostics system notifies a vehicle occupant to pull over orarrange service when a di/dt frequency profile of a subsystem shiftsoutside expected operating conditions. The prognostics system canautomatically take appropriate mitigation actions based on the level ofperformance degradation to ensure safe vehicle operation under degradedperformance.

The prognostics system provides many advantages. For example, theprognostics system can proactively detect wiring and performance issuesbefore the issues become problems and require service. The prognosticssystem provides improved diagnostic ability by detecting abnormalheating of wiring, providing soft-short protection, providing fastershort circuit detection, and detecting misbehaving subsystems. Theprognostics system improves power distribution controls by allowingreduced wire sizes, providing improved under-voltage detection,detecting and eliminating (e.g., disconnecting) high-drain systems thatdrain the vehicle battery, resetting misbehaving systems, and providingredundant power fail-over.

Further, the prognostics system provides the ability to perform acomprehensive end-of-line test before shipping vehicles from thefactory. The prognostics system identifies issues for users during useof the vehicles. The prognostics system allows service personnel todetect issues after service is completed before releasing the vehiclesto users. Furthermore, the data from the prognostics system can becollected and analyzed at back end (e.g., in cloud) to improve futuredesign of vehicle systems. These and other features of the system arenow described below in detail.

The present disclosure is organized as follows. The prognostics systemaccording to the present disclosure is shown and described withreference to FIGS. 1-7. The calibration, measurements, analyses, andmitigation performed by the prognostics system are described in detailwith reference to FIGS. 8-18.

FIG. 1 shows a prognostics system 100 for a vehicle 101 according to thepresent disclosure. The prognostics system 100 comprises a battery 102,a controller 104, and a plurality of subsystems 106-1, 106-2, . . . ,and 106-N (collectively subsystems 106) of the vehicle 101, where N is apositive integer. The battery 102 supplies power to the controller 104and the subsystems 106. The controller 104 controls the subsystems 106.

Examples of the subsystems 106 include a braking subsystem, a steeringsubsystem, a navigation subsystem, a communication subsystem, aninfotainment subsystem, an autonomous subsystem, and so on. Some of thesubsystems 106 may control one or more safety features of the vehicle101 and are called safety subsystems throughout the present disclosure.

The subsystems 106 are connected to the controller 104 and the battery102 via a plurality of switches that also function as fuses (shown inFIGS. 2 and 3) and by a plurality of wires 108 (e.g., cables, wiringharnesses, etc.) and connectors (not shown). Some of the subsystems 106may include components (e.g., sensors, actuators, etc.) that areconnected to the controller 104 and the battery 102 by one or more ofthe wires 108 and connectors.

The controller 104 comprises a measurement module 120 and an analysismodule 122. The measurement module 120 measures di/dt data in variouscurrent loops formed by the wires 108 and the subsystems 106. Theanalysis module 122 analyzes the di/dt data and detects abnormalities inthe wires 108 and the subsystems 106 as described below in detail.

The controller 104 communicates with a remote server 110 via adistributed communications system 112 such as the Internet. Thecontroller 104 can be implemented in many ways. For example, thecontroller 104 may be implemented in a battery management system of thevehicle (not shown). Some of the operations of the controller 104described below may be offloaded to and performed by the server 110 in acloud.

The controller 104 performs various operations as described below indetail. Briefly, the measurement module 120 measures the di/dt dataacross the switches, at various connectors, through the wires 108, andso on. The analysis module 122 processes and analyses the di/dt data toassess the integrity or level of degradation in performance of thewiring and the connections. The integrity of the wiring and theconnections is inversely proportional to the level of degradation inperformance of the wiring and the connections. Based on the analysis,the controller 104 determines whether the degradation requires immediateaction (e.g., switching operation to a redundant subsystem, disabling asubsystem, stopping the vehicle, scheduling service, etc.). Acalibration procedure performed by the controller 104 for theprognostics system 100, the analysis of the di/dt data performed by thecontroller 104 using the calibration data as a reference, and variousmitigation operations performed by the controller 104 based on theanalysis are described below in detail with reference to flowchartsshown in FIGS. 8-18.

FIG. 2 shows an example of the prognostics system 100 that has theability to isolate misbehaving subsystems to prevent power loss and toprovide redundant power to safety subsystems using the single battery102. For example, the controller 104 may be subdivided into a firstcontroller 104-1 and a second controller 104-2 (collectively thecontroller 104). The first controller 104-1 may primarily control thesubsystems 106. For redundancy, some of the subsystems 106 (e.g., safetysubsystems) may be provided with backup subsystems 107-1, 107-2, . . . ,and 107-M (collectively the backup subsystems 107), where M is apositive integer. The second controller 104-2 may communicate with thefirst controller 104-1 and may control the backup subsystems 107.Diagnostics may be implemented in a battery management system, ordiagnostic decisions may be made in a host controller, cloud etc.

The first controller 104-1 performs prognostics to predict wiring faultsand proactively service the subsystems 106 (e.g., by providing resets,isolating, switching to backup subsystems, etc.) using one or moremethods described below in detail with reference to FIGS. 8-18. Thesingle battery 102 is also diagnosable so as to reliably provide powerto active safety subsystems (primary and backup) 106, 107.

The first controller 104-1 controls the subsystems 106 via switches130-1, 130-2, . . . , and 130-X (collectively the switches 130), where Xis a positive integer. The switches 130 operate as smart fuses. Forexample, the switches 130 can include FETs or some other activesemiconductor devices that include a control terminal (e.g., a gate, anexample shown at 131). The first controller 104-1 controls the states ofthe switches 130 by driving the control terminals of the switches 130.By controlling the control terminals of the switches 130, the switches130 can be individually opened and closed, which allows the firstcontroller 104-1 to individually connect and disconnect the subsystems106. For example, the switches 130 provide the ability to individuallyconnect and disconnect the subsystems 106 to and from the battery 102.The switches 130 also operate as fuses, which eliminates the need forwire fuses that cannot be controlled similar to the switches 130 andthat do not allow the first controller 104-1 to individually connect anddisconnect the subsystems 106.

The second controller 104-2 controls the backup subsystems 107 viaswitches 132-1, 132-2, . . . , and 132-Y (collectively the switches132), where Y is a positive integer. The switches 132 also operate assmart fuses. For example, the switches 132 can include FETs or someother active semiconductor devices that include a control terminal(e.g., a gate, an example shown at 133). The second controller 104-2controls the states of the switches 132 by driving the control terminalsof the switches 132. By controlling the control terminals of theswitches 132, the switches 132 can be individually opened and closed,which allows the second controller 104-2 to individually connect anddisconnect the backup subsystems 107 based on signals received from thefirst controller 104-1.

For example, the switches 132 provide the ability to individuallyconnect and disconnect the backup subsystems 107 to and from the battery102 based on the signals received by the second controller 104-2 fromthe first controller 104-1. The switches 1322 also operate as fuses,which eliminates the need for wire fuses that cannot be controlledsimilar to the switches 132 and that do not allow the second controller104-2 to individually connect and disconnect the backup subsystems 107based on signals received from the first controller 104-1.

For example, the first controller 104-1 may identify a problem with oneof the subsystems 106 by analyzing the di/dt data using one of manymethods shown and described below with reference to FIGS. 8-18. Thefirst controller 104-1 may isolate a misbehaving subsystem 106. Thefirst controller 104-1 may disconnect the misbehaving subsystem 106 bycontrolling the corresponding switch 130. The first controller 104-1 maysend a signal to the second controller 104-2 indicating that themisbehaving subsystem 106 is disconnected and that a correspondingbackup subsystem 107 needs to be activated and connected instead.

Upon receiving the signal from the first controller 104-1 indicatingthat the misbehaving subsystem 106 is disconnected and that acorresponding backup subsystem 107 needs to be activated and connectedinstead, the second controller 104-2 activates a switch 132corresponding to the backup subsystem 107 for the disconnectedmisbehaving subsystem 106 and connects the backup subsystem 107 insteadof the disconnected misbehaving subsystem 106.

In addition to the switches 130, 132, the first and second controllers104-1, 104-2 (collectively the controller 104) include temperature,current, and voltage sensors respectively shown as T, C, and V. Thesesensors are explained in further detail below with reference to FIG. 4.

Since the switches 130, 132 are not mere wire fuses and since theswitches 130, 132 have control terminals 131, 133, the switches 130,132are also diagnosable. Due to the control terminals 131, 133, theswitches 130, 132 can be individually controlled and also can becontrolled together (i.e., collectively) by driving their controlterminals 131, 133 using a single signal from the controller 104.Further, all the switches 130, 132 can be opened and closed individuallyas well as together. Furthermore, fusing values for the switches 130,132 can be calibrated at factory or in vehicle to minimize skews.

FIG. 3 shows the configuration of FIG. 2 with the addition of aredundant (i.e., backup) battery 103. The redundant battery 103 is alsodiagnosable. The redundant battery 103 provides a higher level of safetythan in FIG. 2 since the redundant battery 103 can continue to supplypower to a backup subsystem 107 if the battery 102 fails instead of acorresponding primary subsystem 106 failing.

FIG. 4 shows a portion of the controller 104 with the temperature,current, and voltage sensors (shown in dotted ovals numbered 150 and152) distributed in an example of a current loop including the battery102, the switch 130, and the subsystem 106. Using the sensors 150, 152,the controller 104 compares the power to a temperature of the connectionpoints at the sensor locations 150, 152 to identify risk of overheatingdue to a problem such as defective or degrading wiring 108 or connection(e.g., loose contact or corroding contact). Using the sensors 152, thecontroller 104 can identify which fuse is blown (i.e., which switch 130,132 is defective) to the vehicle owner and schedule service.

Using the sensors 152, the controller 104 can identify the current loopconsuming abnormally high amount of current during key off (i.e., whenthe vehicle is turned off), disconnect the subsystem 106 by controllingthe switch 130 in the current loop, and prevent the battery 102 fromdraining, as explained below in detail with reference to FIGS. 15 and16.

Using the sensors 152, the controller can also perform overcurrent andsoft short circuit detection. For example, a soft short circuit mayoccur when ambient temperature is extremely low but may disappear afterthe temperature rises (e.g., during operation of the vehicle). Thecontroller 104 can detect a soft short circuit by setting current versustime threshold and minimum voltage versus time threshold. If anovercurrent condition or a soft short circuit is detected, thecontroller 104 can employ a soft reset for mitigation and recovery.

FIG. 5 shows examples of wiring problems that can be detected by thecontroller 104 in a current loop. For example, at 109-1, a connectionmay be bad due to a poorly crimped wire 108; at 109-2, a wire 108 may bedefective because of a few strands of the wire 108 being cut; at 109-3,a connection may be bad because of a nut being loose, a crimp being bad,or contact being corroded; and so on.

The di/dt analysis of the data collected in the current loop (explainedbelow in further detail with reference to FIGS. 6 and 7) provides anend-to-end analysis of the integrity of the wiring 108 and theconnections in the current loop. The controller 104 analyzes the di/dtdata in frequency domain and checks all connections in the current loop.As seen from FIGS. 6 and 7, contrary to time domain analysis, theanalysis in frequency domain can be performed with low noise sensitivityand at a higher resolution than in time domain.

Based on the analysis of the di/dt data in frequency domain, thecontroller 104 characterizes the impedance of the wiring 108 and theconnections in the current loop. The controller 104 detects degradingperformance of the wiring 108 and the connections (e.g., detectsproblems shown as 109-1, 109-2, 109-3, etc.) before a fault occurs. Thecontroller 104 performs the impedance characterization by analysing thedi/dt data from various nodes (i.e., connection points) in the wiring108 in frequency domain.

Unlike the conventional resistance measurements performed by measuringvoltage and current in time domain that are susceptible to noise, theanalysis of the di/dt data in the frequency domain is largely unaffectedby the noise due to noise filtering built into the analysis in thefrequency domain. Further, by increasing the sampling frequency, theanalysis of the di/dt data in frequency domain can be used to detectabnormalities in the wiring 108 and the connections in the current loopat a higher resolution than when the data is analyzed in time domain.

FIG. 6 shows an example of an analysis of di/dt data in time domain. Forexample, the graph shows curves of di/dt data measured at a clamp of apositive terminal of the battery 102. Each curve represents di/dt datameasured at a different amount of tightness of the clamp. As seen, thechange in the di/dt data in time domain with different amount oftightness of the clamp is insufficient to conclude if the clamp istight, overtight, or loose. No discernable change can be identified overthe noise floor when measuring voltage, current, or power in timedomain.

FIG. 7 shows an example of an analysis of di/dt data in frequencydomain. For example, the graph shows di/dt data sampled at a clamp of apositive terminal of the battery 102. As seen, the di/dt rate decreasesmeasurably from 160 to 162 as the nut at the clamp is loosened. Further,if the sampling rate is increased, the resolution of detecting a loosenut increases.

A change in rise time of a current or voltage signal provides a morediscernable change than a measurement of current, voltage or resistance.For example, a two-fold change in the rise time can be seen with a 1milli-Ohm change in resistance. Accordingly, the di/dt analysis infrequency domain is not only more robust due to low noise sensitivitybut is also scalable since the resolution scales with samplingfrequency.

The following are various methods employed by the prognostics system 100generally and the controller 104 specifically for performing all of theoperations described above. In the following description, the termcontrol generally denotes operations performed by the controller 104.

FIG. 8 shows a method 500 for detecting and disabling a current loopthat drains the battery of the vehicle (e.g., the battery 102 of thevehicle 101 shown in FIG. 1) while the vehicle is turned off. The method500 is shown and described in more detail with reference to FIGS. 15 and16. At 502, control determines if the vehicle is turned off. If thevehicle is turned off, at 504, control detects using the prognosticssystem 100 shown in FIG. 1 if the battery of the vehicle is draining.

If the battery of the vehicle is draining, at 506, control beginsmonitoring current loops in the vehicle. At 508, control detects acurrent loop that is draining the battery (e.g., due to a problem withone or more wires are connections in the current loop) by performing themeasurements and analysis in frequency domain as described above. Basedon the analysis, control opens the current loop (e.g., by disconnectinga subsystem 106 in the current loop using a corresponding switch 130shown in FIG. 1).

The method 500 may inform the vehicle owner of the problem (e.g., bysending a message to a mobile device of the owner or by displaying amessage on the dashboard of the vehicle when the vehicle owner startsthe vehicle). Optionally, after warning the vehicle owner about theproblem and to schedule service, the method 500 may reconnect thedisconnected subsystem (e.g., by using a corresponding switch) when thevehicle owner starts the vehicle.

FIG. 9 shows a method 530 for resetting a misbehaving subsystem (e.g., asubsystem 106 that is not responding, having communication issues, etc.)in the vehicle. At 532, control begins monitoring the subsystems in thevehicle (e.g., the subsystems 106 in the vehicle 101 shown in FIG. 1).At 534, control determines if any of the subsystems in the vehicle ismisbehaving (e.g., not responding, having communication issues, etc.).If any of the subsystems is misbehaving, at 536, control resets themisbehaving subsystem.

For example, control may initially simply restart (i.e., initialize orreboot) the misbehaving subsystem. If that does not solve the problem,control may perform a hardware reset on the misbehaving subsystem bydisconnecting power to the misbehaving subsystem and after waiting for aperiod of time reconnecting the power to the misbehaving system (e.g.,by using a corresponding switch 130).

After performing either type of reset on the misbehaving subsystem, at538, control again determines if the subsystem is still misbehaving. Ifthe subsystem is still misbehaving, at 540, control disconnects themisbehaving subsystem (e.g., by using a corresponding switch 130) andinforms the vehicle owner to schedule service. Control disconnects themisbehaving subsystem if the misbehaving subsystem is not a safetysubsystem (i.e., not controlling one or more safety features of thevehicle). Control follows a different procedure shown and describedbelow with reference to FIG. 10 if the misbehaving subsystem is a safetysubsystem.

FIG. 10 shows a method 560 for switching to a backup subsystem (e.g.,one of the subsystems 107 shown in FIGS. 2 and 3) when a safetysubsystem (e.g., one of the subsystems 106 shown in FIG. 1) in thevehicle is misbehaving (e.g., not responding, having communicationissues, etc.). At 562, control begins monitoring the subsystems in thevehicle (e.g., the subsystems 106 in the vehicle 101 shown in FIG. 1).At 564, control determines if any of the safety subsystems in thevehicle is misbehaving (e.g., not responding, having communicationissues, etc.) by performing the measurements and analysis in frequencydomain as described above.

If any of the safety subsystems is misbehaving, at 566, controldetermines if a backup subsystem for the misbehaving safety subsystem isavailable and operational. If a backup subsystem is available andoperational, at 568, control switches over to the back of subsystem(e.g., by disconnecting the misbehaving subsystem and connecting thebackup subsystem instead using the switches 130, 132 shown in FIGS. 2and 3). If a backup subsystem is unavailable, at 570, control informsthe vehicle owner and optionally stops the vehicle depending on theseverity of the problem with the safety subsystem.

FIG. 11 shows a method 600 for calibrating the prognostics system 100shown in FIG. 1. At 602, the method 600 includes driving the vehicle atdifferent operating temperatures with varying loads. At 604, controlcreates a set of histograms of rate of change of current characteristicsmeasured at different operating temperatures for the plurality ofsubsystems. At 606, control stores the histograms as calibrationreference.

At 608, during normal operation, control generates a histogram of therate of change of current characteristic measured at an operatingtemperature over a drive cycle for one of the subsystems. At 610,control looks up a reference histogram from the stored histograms forthe one of the subsystems based on the operating temperature during thedrive cycle.

At 612, control compares the histogram of the rate of change of currentcharacteristic measured at the operating temperature during the drivecycle to the reference histogram. At 614, control determines adifference between the reference histograms and the histogram of therate of change of current characteristic measured at the operatingtemperature during the drive cycle. Control determines if the differenceis greater than or equal to a predetermined threshold. The predeterminedthreshold is determined as shown and described below with reference toFIG. 12.

At 616, control determines the integrity of the wiring and connectionsassociate with the one of the subsystem based on the difference, andgenerates an indication regarding the integrity of the plurality of thewires and the connections associated with the one of the subsystems(e.g., if the wiring and the connections are normal or abnormal) basedon whether the difference being greater than or equal to thepredetermined threshold. Control may also indicate a type of abnormality(e.g., short circuit, open circuit, overheating, etc.) based on thedifference.

FIG. 12 shows a method 650 for determining the threshold used in themethod 600. At 652, the method 650 includes collecting wire samples. At654, the method 650 includes creating various levels of failure for eachtype of wiring failure (e.g., poor crimp, cut layer, etc.). For example,the failures may include defects such as those shown at 109-1, 109-2,and 109-3 in FIG. 5.

At 656, control sets a diagnostic trouble threshold at a minimum meantime to failure threshold to meet reliability requirements. At 658,control tests the wire samples on either side of the minimum mean timeto failure threshold in simulation. At 660, control determines theresolution of fault detectability. At 662, control adds thedetectability margin to the minimum mean time to failure threshold. Thisthreshold is then used in the method 600 to determine the integrity ofwiring and connections as described above with reference to FIG. 11.

FIG. 13 shows a first method 700 for handling a failure of a wire and/ora connection in a current loop including a subsystem controlling asafety feature of the vehicle. At 702, control measures a rate of changeof current characteristic in frequency domain for a current loopincluding a switch, a subsystem controlling a safety feature of thevehicle, and a plurality of wires connecting the subsystem to a batteryof the vehicle via the switch (e.g., elements 130, 108, 106, and 102)shown in FIG. 1).

At 704, control creates a histogram of the rate of change of currentcharacteristic by performing the measurements and analysis in frequencydomain as described above. At 706, control determines if the histogramis out of limits (e.g., if the difference between the histogram and areference histogram generated during calibration is greater than orequal to a predetermined threshold). Control returns to 702 if thehistogram is not out of limits. If the histogram is out of limits,control sets a diagnostic code at 708 and sends a notification to thevehicle owner at 710 (e.g., to schedule service).

Additionally, if the histogram is out of limits, at 712, controldetermines if the detected abnormality (indicated by the histogram beingout of limits) relates to a safety feature or a feature associated withautonomous driving. If the detected abnormality is related to a safetyfeature and not associated with autonomous driving, then at 714, controlnotifies the driver of the vehicle.

At 716, control determines if a failure due to the detected abnormalityis imminent. If a failure due to the detected abnormality is notimminent, at 718, control issues a warning to the driver of the vehicle(e.g., turns on a service indicator). If a failure due to the detectedabnormality is imminent, at 720, control disables the vehicle operation.

If the detected abnormality is not related to a safety feature and isassociated with autonomous driving, then at 722, control notifies thedriver of the vehicle. At 724, control determines if the driver iscontrolling the vehicle (e.g., if the vehicle is in semi-autonomousmode). If the driver is controlling the vehicle, at 726, controldisables the feature. If the driver is not controlling the vehicle(i.e., if the vehicle is in autonomous mode), then at 728 control stopsthe vehicle.

FIG. 14 shows a second method 750 for handling a failure of a wireand/or a connection in a current loop including a subsystem controllinga safety feature of the vehicle. At 752, control measures a rate ofchange of current characteristic in frequency domain for a current loopincluding a switch, a subsystem controlling a safety feature of thevehicle, and a plurality of wires connecting the subsystem to a batteryof the vehicle via the switch (e.g., elements 130, 108, 106, and 102)shown in FIG. 1).

At 754, control creates a histogram of the rate of change of currentcharacteristic by performing the measurements and analysis in frequencydomain as described above. At 756, control determines if the histogramis out of limits (e.g., if the difference between the histogram and areference histogram generated during calibration is greater than orequal to a predetermined threshold). Control returns to 752 if thehistogram is not out of limits. If the histogram is out of limits,control notifies the driver at 758 (e.g., to schedule service). At 760,control issues a warning to the driver of the vehicle (e.g., turns on aservice indicator).

At 762, control determines if the detected abnormality (indicated by thehistogram being out of limits) relates to a safety feature or a featureassociated with autonomous driving. If the detected abnormality isrelated to a safety feature and not associated with autonomous driving,then at 764, control disables the feature.

If the detected abnormality is not related to a safety feature and isassociated with autonomous driving, then at 766, control determines ifthe driver is controlling the vehicle (e.g., if the vehicle is insemi-autonomous mode). If the driver is controlling the vehicle, then at764, control disables the feature. If the driver is not controlling thevehicle (i.e., if the vehicle is in autonomous mode), then at 768control stops the vehicle.

FIG. 15 shows a method 800 to detect and disable a current loop that isdraining the battery of the vehicle when the vehicle is turned off. At802, control measures a load current of a subsystem in a current loop.At 804, control determines if the load current is greater than or equalto a maximum threshold. Control returns to 802 if the load current isless than the maximum threshold.

If the load current is greater than or equal to the maximum threshold,at 806 control increments a first counter by 1. The first counter helpsdefine a number of times the following operations can be attemptedbefore notifying the vehicle owner. At 808, control sets a diagnosticcode indicating that the load current is high (i.e., greater than orequal to the maximum threshold).

At 810, control determines if the first counter is greater than 1.Control returns to 802 if the first counter is not greater than 1. Ifthe first counter is greater than 1, at 812, control initiates a softreset for the subsystem (i.e., control does not disconnect and reconnectpower to the subsystem). At 814, after the soft reset, controldetermines if the load current is greater than or equal to the maximumthreshold. Control returns to 802 if the load current is less than themaximum threshold.

If the load current is still greater than or equal to the maximumthreshold even after the soft reset, at 816, control increments a secondcounter by 1. At 818, control resets power to the subsystem (this is thehardware reset described above). At 820, control increments a thirdcounter by 1. At 822, control sets the power on reset (POR) servicealert as true.

At 824, control determines if the third counter is greater than zero.Control returns to 802 if the third counter is not greater than zero. Ifthe third counter is greater than zero, at 826, control sets the key offcustomer alert as true. Control returns to 802.

The method 800 assumes that the vehicle is in key off (i.e., turned off)at the beginning. If the issue is not resolved by the hard reset, themethod 800 notifies the customer (e.g., via a diagnostic code, a phoneapp, an engine light, etc.) that the vehicle needs to be serviced. Themethod 800 may also notify the customer at the time of the event. Themethod 800 can also be used during vehicle operation. However, duringvehicle operation, the method 800 may not wait for key on or key off tonotify the driver.

FIG. 16 shows a method 850 to detect and isolate a misbehaving subsystemwhile the vehicle is turned off. The method 850 is similar to the method800 shown and described above with reference to FIG. 15. The method 850can be performed with the vehicle turned off (i.e., with key off) orduring vehicle operation (i.e., with key on). When the method 850 isperformed with the vehicle turned off (i.e., with key off), the customernotification described below can be performed at any time although thecustomer notification may be performed after key on (i.e., after thevehicle is turned on) to save battery power.

At 852, control monitors a misbehaving subsystem. For example, thesubsystem may be nonresponsive, may have a communication issue, and soon. At 854, control determines based on the monitoring if the subsystemhas failed. Control returns to 852 if the subsystem has not failed. Ifthe subsystem has failed, at 856, control increments a first counterby 1. At 858, control sets a diagnostic code to indicate that thesubsystem has failed.

At 860, control determines if the first counter is greater than 1.Control returns to 852 if the first counter is not greater than 1. Ifthe first counter is greater than 1, at 862, control initiates a softreset for the subsystem (i.e., control does not disconnect and reconnectpower to the subsystem). At 864, after the soft reset, controldetermines if the subsystem has failed. Control returns to 852 if thesubsystem has not failed.

If the subsystem has failed after the soft reset, at 866, controlincrements a second counter by 1. At 868, control resets power to thesubsystem by opening and subsequently closing the switch that connectspower to the subsystem. At 870, control increments a third counter by 1.At 872, control sets the power on reset (POR) service alert as true.

At 874, control determines if the third counter is greater than zero.Control returns to 852 if the third counter is not greater than zero. Ifthe third counter is greater than zero, at 876, control sets the key offcustomer alert as true. Control returns to 852.

FIG. 17 shows a method 900 for verifying integrity of wiring in avehicle before shipping the vehicle from the factory. At 902, the method900 determines if the vehicle is ready to ship from the factory. At 904,if the vehicle assembly is complete and the vehicle is ready to ship,control verifies the wiring and connections in the vehicle using theprognostics system 100 shown in FIG. 1.

At 906, control determines if any defects are found in the wiring andconnections in the vehicle. If any defects are found, at 908, the method900 includes fixing the defects. At 910, the method 900 informs qualitycontrol the details about the defects found and the steps taken toremedy the defects, including the parts used, the labor involved, thedelay caused in shipping the vehicle, and so on.

The method 900 repeats steps 904, 906, 908 and, 910 until no defects arefound in the wiring and connections. When no defects are found in thewiring and connections in the vehicle, the method 900 proceeds to 912.At 912, the method 900 certifies that the vehicle is ready to ship fromthe factory.

FIG. 18 shows a method 950 for verifying integrity of wiring in avehicle after servicing the vehicle at a service center before returningthe vehicle to the customer. At 952, the method 950 determines if thevehicle service is completed. At 954, if the vehicle service iscompleted, control verifies the wiring and connections in the vehicleusing the prognostics system 100 shown in FIG. 1.

At 956, control determines if any defects are found in the wiring andconnections in the vehicle. If any defects are found, at 958, the method950 includes fixing the defects. At 960, the method 950 informs qualitycontrol the details about the defects found and the steps taken toremedy the defects, including the parts used, the labor involved, thedelay caused in returning the vehicle to the customer, and so on.

The method 950 repeats steps 954, 956, 958 and, 960 until no defects arefound in the wiring and connections in the vehicle. When no defects arefound in the wiring and connections in the vehicle, the method 950proceeds to 962. At 962, the method 950 certifies that the vehicle isready to be returned to the customer.

The teachings of the present disclosure are applicable tonon-autonomous, semi-autonomous, and autonomous vehicles. Further, theteachings are also applicable to any other type of vehicle such as shipsand aircrafts that involve multiple subsystems interconnected byextensive wiring. Further, the teaching are also applicable toelectrical systems employing a backplane in which multiple subsystemsare installed. Although a backplane uses printed circuit boards thatinclude conductive traces, which reduces the amount of wires used in theelectrical systems, the conductive traces can have integrity issuesincluding short circuits, open circuits, and defective connections tocircuit boards and power supplies connected to the backplane. Theseissues can be detected using the teachings of the present disclosure.Other applications of the teachings are contemplated.

The foregoing description is merely illustrative in nature and is notintended to limit the disclosure, its application, or uses. The broadteachings of the disclosure can be implemented in a variety of forms.Therefore, while this disclosure includes particular examples, the truescope of the disclosure should not be so limited since othermodifications will become apparent upon a study of the drawings, thespecification, and the following claims. It should be understood thatone or more steps within a method may be executed in different order (orconcurrently) without altering the principles of the present disclosure.Further, although each of the embodiments is described above as havingcertain features, any one or more of those features described withrespect to any embodiment of the disclosure can be implemented in and/orcombined with features of any of the other embodiments, even if thatcombination is not explicitly described. In other words, the describedembodiments are not mutually exclusive, and permutations of one or moreembodiments with one another remain within the scope of this disclosure.

Spatial and functional relationships between elements (for example,between modules, circuit elements, semiconductor layers, etc.) aredescribed using various terms, including “connected,” “engaged,”“coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and“disposed.” Unless explicitly described as being “direct,” when arelationship between first and second elements is described in the abovedisclosure, that relationship can be a direct relationship where noother intervening elements are present between the first and secondelements, but can also be an indirect relationship where one or moreintervening elements are present (either spatially or functionally)between the first and second elements. As used herein, the phrase atleast one of A, B, and C should be construed to mean a logical (A OR BOR C), using a non-exclusive logical OR, and should not be construed tomean “at least one of A, at least one of B, and at least one of C.”

In the figures, the direction of an arrow, as indicated by thearrowhead, generally demonstrates the flow of information (such as dataor instructions) that is of interest to the illustration. For example,when element A and element B exchange a variety of information butinformation transmitted from element A to element B is relevant to theillustration, the arrow may point from element A to element B. Thisunidirectional arrow does not imply that no other information istransmitted from element B to element A. Further, for information sentfrom element A to element B, element B may send requests for, or receiptacknowledgements of, the information to element A.

In this application, including the definitions below, the term “module”or the term “controller” may be replaced with the term “circuit.” Theterm “module” may refer to, be part of, or include: an ApplicationSpecific Integrated Circuit (ASIC); a digital, analog, or mixedanalog/digital discrete circuit; a digital, analog, or mixedanalog/digital integrated circuit; a combinational logic circuit; afield programmable gate array (FPGA); a processor circuit (shared,dedicated, or group) that executes code; a memory circuit (shared,dedicated, or group) that stores code executed by the processor circuit;other suitable hardware components that provide the describedfunctionality; or a combination of some or all of the above, such as ina system-on-chip.

The module may include one or more interface circuits. In some examples,the interface circuits may include wired or wireless interfaces that areconnected to a local area network (LAN), the Internet, a wide areanetwork (WAN), or combinations thereof. The functionality of any givenmodule of the present disclosure may be distributed among multiplemodules that are connected via interface circuits. For example, multiplemodules may allow load balancing. In a further example, a server (alsoknown as remote, or cloud) module may accomplish some functionality onbehalf of a client module.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes, datastructures, and/or objects. The term shared processor circuitencompasses a single processor circuit that executes some or all codefrom multiple modules. The term group processor circuit encompasses aprocessor circuit that, in combination with additional processorcircuits, executes some or all code from one or more modules. Referencesto multiple processor circuits encompass multiple processor circuits ondiscrete dies, multiple processor circuits on a single die, multiplecores of a single processor circuit, multiple threads of a singleprocessor circuit, or a combination of the above. The term shared memorycircuit encompasses a single memory circuit that stores some or all codefrom multiple modules. The term group memory circuit encompasses amemory circuit that, in combination with additional memories, storessome or all code from one or more modules.

The term memory circuit is a subset of the term computer-readablemedium. The term computer-readable medium, as used herein, does notencompass transitory electrical or electromagnetic signals propagatingthrough a medium (such as on a carrier wave); the term computer-readablemedium may therefore be considered tangible and non-transitory.Non-limiting examples of a non-transitory, tangible computer-readablemedium are nonvolatile memory circuits (such as a flash memory circuit,an erasable programmable read-only memory circuit, or a mask read-onlymemory circuit), volatile memory circuits (such as a static randomaccess memory circuit or a dynamic random access memory circuit),magnetic storage media (such as an analog or digital magnetic tape or ahard disk drive), and optical storage media (such as a CD, a DVD, or aBlu-ray Disc).

The apparatuses and methods described in this application may bepartially or fully implemented by a special purpose computer created byconfiguring a general purpose computer to execute one or more particularfunctions embodied in computer programs. The functional blocks,flowchart components, and other elements described above serve assoftware specifications, which can be translated into the computerprograms by the routine work of a skilled technician or programmer.

The computer programs include processor-executable instructions that arestored on at least one non-transitory, tangible computer-readablemedium. The computer programs may also include or rely on stored data.The computer programs may encompass a basic input/output system (BIOS)that interacts with hardware of the special purpose computer, devicedrivers that interact with particular devices of the special purposecomputer, one or more operating systems, user applications, backgroundservices, background applications, etc.

The computer programs may include: (i) descriptive text to be parsed,such as HTML (hypertext markup language), XML (extensible markuplanguage), or JSON (JavaScript Object Notation) (ii) assembly code,(iii) object code generated from source code by a compiler, (iv) sourcecode for execution by an interpreter, (v) source code for compilationand execution by a just-in-time compiler, etc. As examples only, sourcecode may be written using syntax from languages including C, C++, C#,Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl,Pascal, Curl, OCaml, Javascript®, HTML5 (Hypertext Markup Language 5threvision), Ada, ASP (Active Server Pages), PHP (PHP: HypertextPreprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, VisualBasic®, Lua, MATLAB, SIMULINK, and Python®.

What is claimed is:
 1. A system for a vehicle comprising: a battery ofthe vehicle; a plurality of switches connected to the battery; aplurality of subsystems of the vehicle connected to the battery via theswitches and wires; and a controller configured to: control the switchesand the subsystems; identify a variation in a rate of change of currentcharacteristic in frequency domain for a current loop including one ofthe switches, one of the subsystems, and a plurality of the wires;generate a histogram of the rate of change of current characteristic atan operating temperature for the one of the subsystems; and determineintegrity of the plurality of the wires and connections of the wires inthe current loop based on a comparison between the histogram and one ormore histograms of rate of change of current characteristics measured atdifferent operating temperatures for the plurality of subsystems.
 2. Thesystem of claim 1 wherein the controller generates an indicationregarding the integrity of the plurality of the wires and connections ofthe wires in the current loop in response to the integrity being lessthan or equal to a first threshold.
 3. The system of claim 1 wherein thecontroller generates an indication regarding the integrity of theplurality of the wires and connections of the wires in the current loopin response to the integrity being less than or equal to a firstthreshold, and disconnects the one of the subsystems from the currentloop by controlling the one of the switches in response to the integritybeing less than or equal to a second threshold that is greater than thefirst threshold.
 4. The system of claim 1 wherein the controllercharacterizes operation of the one of the subsystems based on thevariation in the rate of change of current characteristic for thecurrent loop and determines based on the characterization whether todisconnect the one of the subsystems from the current loop bycontrolling the one of the switches.
 5. The system of claim 1 whereinthe controller characterizes operation of the one of the subsystemsbased on the variation in the rate of change of current characteristicfor the current loop, and based on the characterization controls the oneof the switches to disconnect the one of the subsystems from the currentloop and subsequently reconnect the one of the subsystems to the currentloop.
 6. The system of claim 5 wherein the controller characterizes theoperation of the one of the subsystems and disconnects the one of thesubsystems based on the characterization when the vehicle is turned off.7. The system of claim 1 wherein based on the variation in the rate ofchange of current characteristic for the current loop, the controllerdisconnects the one of the subsystems from the current loop andactivates a backup subsystem powered by the battery.
 8. The system ofclaim 1 wherein based on the variation in the rate of change of currentcharacteristic for the current loop, the controller disconnects the oneof the subsystems from the current loop and activates a backup subsystempowered by a different battery.
 9. The system of claim 1 wherein thecontroller determines the integrity of the plurality of the wires andconnections of the wires additionally based on one or more of a voltagemeasurement and a temperature measurement in the current loop.
 10. Thesystem of claim 1 wherein the controller is configured to: compare thehistogram to one of the histograms corresponding to the operatingtemperature; determine a difference between the histogram and the one ofthe histograms; determine the integrity of the plurality of the wiresand connections of the wires in the current loop based on thedifference; and generate an indication regarding the integrity of theplurality of the wires and connections of the wires in the current loopin response to the difference being greater than or equal to apredetermined threshold.
 11. A method comprising: connecting a batteryto a plurality of subsystems of a vehicle via a plurality of switchesand wires; controlling the switches and the subsystems; measuringcurrent and analyzing, without using reflectometry, a variation in arate of change of current characteristic in frequency domain for acurrent loop including one of the switches, one of the subsystems, and aplurality of the wires; generating a histogram of the rate of change ofcurrent characteristic at an operating temperature for the one of thesubsystems; determining an integrity of the plurality of the wires andconnections of the wires in the current loop based on a comparisonbetween the histogram and one or more histograms of rate of change ofcurrent characteristics measured at different operating temperatures forthe plurality of subsystems.
 12. The method of claim 11 furthercomprising detecting at least one of a defective wire and a defectiveconnection of one of the wires in the current loop.
 13. The method ofclaim 11 further comprising: generating an indication regarding theintegrity of the plurality of the wires and connections of the wires inthe current loop in response to the integrity being less than or equalto a first threshold; and disconnecting the one of the subsystems fromthe current loop by controlling the one of the switches in response tothe integrity being less than or equal to a second threshold that isgreater than the first threshold.
 14. The method of claim 11 furthercomprising: characterizing operation of the one of the subsystems basedon the variation in the rate of change of current characteristic for thecurrent loop; and determining based on the characterization whether todisconnect the one of the subsystems from the current loop bycontrolling the one of the switches.
 15. The method of claim 11 furthercomprising: characterizing operation of the one of the subsystems basedon the variation in the rate of change of current characteristic for thecurrent loop; and based on the characterization, controlling the one ofthe switches to disconnect the one of the subsystems from the currentloop and subsequently reconnect the one of the subsystems to the currentloop.
 16. The method of claim 15 further comprising: characterizing theoperation of the one of the subsystems when the vehicle is turned off;and disconnecting the one of the subsystems based on thecharacterization when the vehicle is turned off.
 17. The method of claim11 further comprising based on the variation in the rate of change ofcurrent characteristic for the current loop: disconnecting the one ofthe subsystems from the current loop; and activating a backup subsystempowered by the battery.
 18. The method of claim 11 further comprisingbased on the variation in the rate of change of current characteristicfor the current loop: disconnecting the one of the subsystems from thecurrent loop; and activating a backup subsystem powered by a differentbattery.
 19. The method of claim 11 further comprising determining theintegrity of the plurality of the wires and connections of the wiresadditionally based on one or more of a voltage measurement and atemperature measurement in the current loop.
 20. The method of claim 11further comprising: comparing the histogram to one of the histogramscorresponding to the operating temperature; determining a differencebetween the histogram and the one of the histograms; determining theintegrity of the plurality of the wires and connections of the wires inthe current loop based on the difference; and generating an indicationregarding the integrity of the plurality of the wires and connections ofthe wires in the current loop in response to the difference beinggreater than or equal to a predetermined threshold.